<div class="panel panel-primary">
    <div class="panel-heading">双向绑定</div>
    <div class="panel-body">
      <test-child-binding [(size)]="fontSizePx"></test-child-binding>
      <div [style.font-size.px]="fontSizePx">Resizable Text</div>
    </div>
  </div>
